WO2014201502A1

WO2014201502A1 - A modular building structure and method of assembly of a modular building structure

Info

Publication number: WO2014201502A1
Application number: PCT/AU2014/000636
Authority: WO
Inventors: Dale Howard ROBERTSON
Original assignee: Robertson Dale Howard
Priority date: 2013-06-19
Filing date: 2014-06-19
Publication date: 2014-12-24

Abstract

A building unit of a modular building structure including an outer wall assembly comprising a pair of opposing outer side walls each with an upper edge, a set of tie beams each of which connects to and extending between the upper edge of each outer side wall, a pair of opposing outer end walls for connecting to and extending between the outer side walls, and a pre-assembled living compartment with an internal wall assembly, a floor and a ceiling. The internal wall assembly including a pair of opposing internal side walls and a pair of opposing internal ends walls connected to and extending between the floor and the ceiling. The internal side walls and the internal end walls define a floor space of the living compartment. The outer wall assembly is assembled about the pre-assembled living compartment when completing construction of the building unit.

Description

A MODULAR BUILDING STRUCTURE AND METHOD OF ASSEMBLY OF A

MODULAR BUILDING STRUCTURE

Introduction

[0001 ] The present invention relates generally to the building and construction industries. The invention has particular application to a modular building structure for either temporary or permanent use and so will be generally described in this context. However, the invention may have other uses. For example, the individual building units contemplated for use in the modular building structure of the present invention need not be incorporated into an overall building structure, and so the invention is to be also understood as extending to these and other potential applications.

Background of Invention

[0002] Conventional building and construction techniques, including those used for conventional multi-storey buildings, require on-site construction and fit-out. This, in turn, limits the speed and order with which construction and fit-out can proceed, as one task often cannot be commenced until another task has been completed. Moreover, with conventional techniques, construction cannot commence on a given floor until the underlying level has been built, which further slows the building process.

[0003] On-site construction and fit-out generally necessitates the use of a local workforce, which may present difficulties in remote locations or areas where there is no ready and experienced workforce available. If it is required to import a foreign workforce then this can add considerably to the cost of construction.

[0004] Further, the quality of such builds can be affected by the skill of the workforce available, and can result in a less than desired build quality. Also if different work forces are involved in different parts of a building or fit-out then differing quality fishes may result, which is undesirable.

[0005] Maintaining confidentiality with regard to a new build can be difficult or impossible to achieve with conventional multi-storey building techniques, given that construction happens on-site in the presence of a large number of tradesmen and other individuals. This can have adverse commercial repercussions for the property developer and construction company.

[0006] Difficulty in attracting finance can also be an issue for many property developers and building construction companies, particularly those involved in overseas based building projects.

[0007] Finally, conventional on-site building techniques often necessitate undesirably complex building repairs or modifications if and when required, since repairs and modification generally must be undertaken on-site. This can cause major disruption to the building occupants.

[0008] It would therefore be desirable to provide a solution for addressing one or more of the drawbacks of conventional building and construction techniques referred to above.

Summary of Invention

[0009] According to one aspect of the present invention, there is provided a building unit of a modular building structure. The building unit includes:

- an outer wall assembly having a pair of opposing outer side walls, with each of the outer side walls including an upper edge. The outer wall assembly also includes a set of tie beams with each tie beam for connecting to and extending between the upper edge of each outer side wall. The outer wall assembly further includes a pair of opposing outer end walls, with the outer end walls provided for connecting to and extending between the outer side walls.

- a pre-assembled living compartment. The living compartment includes a floor and a ceiling, and an internal wall assembly including a pair of opposing internal side walls connected to and extending between the floor and the ceiling. The pre- assembled living compartment also includes a pair of opposing internal end walls connected to and extending between the floor and the ceiling. The internal side walls and the internal end walls define a floor space of the living compartment. [0010] The outer wall assembly is assembled about the pre-assembled living compartment when completing construction of the building unit.

[001 1 ] The above referred arrangement provides a unique arrangement readily allowing for either on-site or off-site construction of a building unit. Moreover, a number of such building units may be manufactured quickly and cost effectively, and may be quickly and efficiently assembled together into a modular building structure. The applicant envisages multiple building units of the type referred to above may be used in the construction of a multiple storey building structure, such as a hotel, or other buildings having multiple living compartments or rooms of substantially the same floor size. The invention can of course extend to building structures having living compartments or differing room sizes, if required.

[0012] Reference to a living compartment is to be understood in a non-limiting sense. The (or each) living compartment may be configured for any specific use, including living quarters, temporary living quarters, office space, or any other practical configuration.

[0013] In a particularly preferred embodiment, each building unit includes a pair of pre-assembled living compartments, with the living compartments separated by a shared floor.

[0014] The outer end walls and outer side walls are preferably manufactured from profiled or corrugated sheet steel. Such an arrangement is desirable, because it provides each building unit with inherent strength, and further allows the building units to be stacked in a multi-storey arrangement in a manner not dissimilar to the stacking of freight containers.

[0015] The outer wall assembly preferably includes corner sections and possibly also top and bottom rails to further enhance the inherent strength of the outer wall assembly, and to facilitate ready connection and stacking of the units. These components may be weight bearing. [0016] It is envisaged that the pre-assembled living compartment would include practically all of its intended fixtures and fittings, prior to assembly of the outer wall assembly about the living compartment. It is envisaged that the supply of a finished or substantially finished pre-assembled living compartment would potentially enhance the rate of construction of the overall building structure.

[0017] It may be that the building structure involves arranging multiple building units in a side-by-side arrangement, and possibly also in an end-on-end arrangement, as well as in a stacked arrangement. Whatever arrangement of multiple building units is desired in the design of a specific building, it is envisaged that each unit would be connected to each adjacent unit so as to provide overall structural rigidity and integrity to the building structure. Adjacent units may, for example, be welded together, or they may be otherwise permanently connected together. Alternatively, the building units may be releasably connected together in a similar manner to the releasable connection arrangement used for connecting adjacent freight containers. If a releasably connection arrangement is utilised then it may be desired to include a safety arrangement preventing inadvertent disconnection of the building units, which may adversely affect the structural integrity of the overall building structure.

[0018] So far, the invention has been generally described in the context of a building unit for use in the construction of a modular building structure. However, the invention is also directed to a method of manufacturing a building unit of a modular building structure. The method includes the steps of:

- assembling a living compartment of the building unit, the living compartment including a floor, a ceiling and an internal wall assembly. The internal wall assembly includes a pair of opposing internal side walls connected to and extending between the floor and the ceiling, and a pair of opposing internal end walls connected to and extending between the floor and the ceiling. The internal side walls and the internal end walls define a floor space of the living compartment.

- Lifting the living compartment and placing it into a jig. - Lifting a pair of opposing outer side walls and placing them into the jig on opposing sides of the living compartment.

- Connecting the outer side walls to the floor.

- Connecting each tie beam of a set of tie beams between an upper edge of each outer side wall; and

- Connecting a pair of opposing outer end walls to and extending between the outer side walls and to the floor.

[0019] The method preferably also includes one or more of:

- Connecting the outer side walls to the floor by welding;

- Connecting each tie beam between the upper edge of each outer side wall by welding; and

- Connecting the opposing end walls to and extending between the outer side walls by welding.

[0020] It is envisaged that the method preferably also includes the step of assembling a second living compartment of the building unit; and lifting the second living compartment and placing it into the jig prior to lifting the pair of opposing outer side walls into the jig.

[0021 ] If a second living compartment is provided, then it is envisaged that a shared floor would be fitted between the living compartment and the second living compartment.

[0022] The step of connecting the opposing outer end walls to and extending between the outer side walls preferably include welding a corner connector between each respective pair of outer end walls and outer side walls.

[0023] The invention also relates to a method of manufacturing a modular building structure, which includes manufacturing a plurality of building units of the type referred to above, and then stacking (or otherwise arranging) and then connecting together two or more of the building units to create the modular building structure. Brief Description of Drawings

[0024] It will now be convenient to hereinafter describe preferred embodiments of the invention with reference to the accompanying drawings. The particularity of the drawings is to be understood as not limiting the preceding broad description of the invention.

[0025] Figure 1 is a schematic flow diagram of the steps involved in manufacturing a building unit for use in constructing a modular building structure from a plurality of separate building units according to one embodiment of the present invention;

[0026] Figure2 is a side view of an outer side wall of the building unit shown in Figure 1 ;

[0027] Figure 3 is side view of an outer end wall of the building unit shown in Figure 1 ;

[0028] Figure 4 is a sectional view of part of the wall structure used in the manufacture of the outer side wall and outer end wall shown in Figure 1 ;

[0029] Figure 5 is a plan view of the floor plan of the outer side walls and the outer end walls of the building unit shown in Figure 1 ;

[0030] Figure 6 is a plan view of the roof plan of the building unit shown in Figure

1 ;

[0031 ] Figure 7 is a plan view of a number of beam and column sections used in the manufacture of the building unit shown in Figure 1 .

[0032] Figure 8 is a view of the framing used in the floor of the building unit shown in Figure 1 .

[0033] Figure 9 is a perspective view of double male-male locking mechanism 90 utilised in connecting adjacent building units together.

[0034] Figure 10 is an end view of the locking mechanism 90 of Figure 9.

[0035] Figure 1 1 is a side view of the locking mechanism 90 of Figure 9.

[0036] Figure 12 is a side view of a locking pin 92 utilised in connecting adjacent building units together, when used in conjunction with the mechanism 90 of Figure 9 or the cone 94 of Figure 13. [0037] Figure 13 is a plan view of a weldable cone 94 for welding to the outside of a building unit, and with a locking hole utilised in connecting adjacent building units together.

[0038] Figure 14 is an end view of the weldable cone 94 illustrated in Figure 13.

[0039] Figure 15 is a perspective view of the weldable cone 94 illustrated in Figure 13.

[0040] Figure 16 is a side view of the weldable cone illustrated in Figure 13. Detailed Description

[0041 ] Referring to the drawings, there is illustrated a building unit 10 (see Stages 1 1 and 12 of Figure 1 ) of a modular building structure 12 (see Stage 13 of Figure 1 ).

[0042] The building unit 10 includes an outer wall assembly 14 having a pair of opposing outer side walls 16. The outer side walls 16 each include an upper edge 18. A set of tie beams is provided, with each tie beam 20 provided for connecting to and extending between the upper edge 18 of each outer side wall 16. A pair of opposing outer end walls 22 is also provided. As can be seen, the outer end walls 22 are connected to and extend between the outer side walls 16 so as to define a generally rectangular space 24, which includes side openings 26.

[0043] The outer end walls 22 and outer side walls 16 are manufactured from profiled sheet steel of approximately 2.0mm thickness, and of a similar type, cross- sectional shape and thickness to that used in the construction of container freight side walls (although our outer suitable designs of the outer side and end walls 16, 22 may also be used). In this regard, Figure 1 illustrates one potential concept of the invention, whereby an existing freight container FC (see Stage 1 to 5 of Figure 1 ) is de-constructed and, from the de-constructed container, the freight container side walls and roof of are cut into the desired shapes to provide the outer side walls 16 and the outer end walls 22. The outer side walls 16 may be obtained from the side walls of the freight container FC; while the outer end walls 22 may, for example, be obtained from the roof of the freight container. [0044] The use of a deconstructed freight container provides a potentially ready and economical source for obtaining the outer side walls 16 and outer end walls 22, particularly if a ready and cost effective workforce is available to undertake the de- construction work. The shipping containers used could be reconditioned, thus potentially further reducing costs, although new containers may be used if desired.

[0045] The applicant also envisages that a more preferred solution for obtaining the outer side walls 16 and outer end walls 22 involves them being manufactured and supplied already cut to the desired size and shape. In so doing, there is no need to de-construct an existing freight container, which can be time consuming and therefore relatively costly, although it may be feasible depending on the available labour costs.

[0046] The building unit 10 also includes a pair of pre-assembled living compartments 28 (or pods). Each living compartment 28 includes a sandwich panel floor 30 and a sandwich panel ceiling 32. Each compartment 28 also includes a sandwich panel internal wall assembly including a pair of opposing internal side walls 34 connected to and extending between the floor 30 and the ceiling 32, and a pair of opposing internal end walls 36 connected to and extending between the floor 30 and the ceiling 32. The internal side walls 34 and the internal end walls 36 define a floor space of each living compartment 28.

[0047] It is to be appreciated that each living compartment 28 may be set up as desired for any practical application. They may each include more than one room. For example, the room layout of each compartment 28 may be set up as hotel accommodation, with a bedroom, separate bathroom and basic kitchen facilities. As another example, each compartment 28 may be set up as a dormitory room for students, or as office space.

[0048] It can be seen that each living compartment 28 includes a window 40, and a doorway 42. A door and door frame (not shown) would be typically fitted to the doorway 42. Both doorways 42 open onto a shared floor space 44 defining a corridor area. [0049] It is envisaged that each pre-assembled living compartment 28 includes all or at least most of the necessary fixtures and fittings prior to assembling the outer side and end walls 16, 22 about the compartment 28 (two substantially completed compartments 28 are shown in Stage 8 of Figure 1 ). Such a process is potentially very desirable, because it allows the compartments 28 to be substantially completed off-site and then (if required) delivered to another site for assembly of the side and end walls 16, 22, and finally transporting and installing the substantially completed building unit 10 into place as part of the overall building structure shown in Stage 13 of Figure 1 .

[0050] It can be seen that the modular building structure 12 shown in Stage 13 of Figure 1 includes a plurality of building units 10. The specific structure 12 is shown is a three-level tiered arrangement, with three units 10 provided for the lower floor 50, two units 10 provided for the middle floor 52, and a single unit 10 provided for the upper floor. This specific structure 12 is shown for illustrative purposes only. Any number of units 10 may be provided in the construction of the structure 12. The units 10 need not be tiered in the manner shown, and the structure 12 need not be limited to a footprint of three units 10, nor to a height of three units.

[0051 ] It is envisaged that each of the units 10 would be securely connected by welding or other suitable arrangement to each adjacent unit, thereby providing an inherently secure and stable structure 12. More preferably, however, the arrangements illustrated in Figures 9 to 16 are utilised to connect adjacent units 1 0 together in a manner not dissimilar to that used for connecting adjacent freight container together. Such an arrangement has not been contemplated for the building and construction industries as far as the applicant is aware. Such an arrangement is desirable because it allows for quick timeframes to lock the units 10 together to BCA (or equivalent) standards to allow speedy erection of the building structure 12. This also avoids the need for welders or other time consuming processes to erect the building and make it safe. [0052] One of the unique aspects of the present invention is the potential speed and efficiency with which the building structure 12 can be assembled. This is at least partly because each building unit 10 can be separately manufactured off -site and delivered (as shown in Stage 12 of Figure 1 ) in its substantially completed form to then be connected into position to adjacent building units in the construction of the structure 12. If production facilities allow for it, then multiple building units 10 may be manufactured at the same time, either in the same facility or in two or more facilities operating in parallel. While it is envisaged that the building units would be manufactured off-sire, this does not preclude them being manufactured on-site, if convenient to do so.

[0053] A typical method of manufacturing a single building unit 10 is illustrated in Figure 1 . This method may be repeated for each building unit 10 used in the construction of an overall building structure 12.

[0054] The method includes assembling each of the living compartments 28 of the building unit 10 in a manner shown in Stages 6 through 8 of Figure 1 . In Stage 6, the floor 30 is assembled from a series of steel beams 60, which are welded to side rails 62, with a pair of end rails 64 welded to and between the side rails 62, and the overlying floor surface 30 laid down. In Figure 8 only some of the beams 60 are labelled. Once the floor 30 has been assembled, sandwich panels are used for the internal side walls 34 and internal end walls 36, which are respectively mounted to the side rails 62 and end rails 64. The ceiling 32 is then fitted.

[0055] The two living compartments 28 are then integrated into a completed building unit 10. This may be done at the same facility where the living compartments 28 are assembled, it may occur at an alternative facility - requiring transport of the compartments 28 thereto, or it may occur on-site.

[0056] Integration of the compartments 28 in the building unit 10 involves lifting and placing the compartments into a jig (not shown), wherein Stages 9 and 10 shown in Figure 1 are undertaken. The outer side walls 16 are also lifted and placed into the jig on opposite sides of the compartment 28, whereafter the side walls are welded to the floor 30. Each tie beam 20 of a set of tie beams is then welded between the upper edges of outer side walls 16.

[0057] The opposing outer end walls 22 are then lifted into the jig and, once in position, are welded to and extend between the outer side walls 16. In fact, vertically extending sections may be provided at and extend upwardly from the floor frame at each of its four corners 70. The outer side and end walls 16, 22 may be welded to these corners sections.

[0058] It can be seen from the above paragraphs and Stages 9 and 10 of Figure 1 that the outer wall assembly is assembled about the pre-assembled living compartments 28 when completing construction of the building unit 10.

[0059] As shown in Stage 10 of Figure 1 , a shared floor 72 and roof structure 74 are welded to and between the two living compartments 28.

[0060] The building units 10 may be of any suitable dimensions.

[0061 ] The completed building units 10, once delivered on-site, are stacked or otherwise suitably arranged together and then inter-connected to create the desired modular building structure 12.

[0062] Stages 1 through 5 of Figure 1 , illustrate a freight container FC being deconstructed to obtain the outer side walls 16 and outer end walls 22. While this is possible and, in some circumstances a preferred approach, it is envisaged that a more preferred approach would be to have the outer side and end walls 16, 22 specifically manufactured, thereby obviating the need to use a freight container.

[0063] The above discussion on manufacture of the units 10 is provided as an overview, in so far as a number of minor steps have not been detailed. Some of these steps are referred to below. [0064] The modular building structure 12 is built from multiple building units 10 utilising four distinct stages, which are described in further detail below:

STAGE 1 - STEEL STRUCTURE

[0065] The steel rails for the floor 30, outer side walls 16, outer end walls 22, tie beams 20, corner columns, corner castings, top rails, and bottom rails are supplied. Some or all of these components may be Corten Steel, thereby eliminating the need for painting, and form a stable rust-like appearance if exposed to the weather.

[0066] Some of these components may then be welded together, preferably off- site, but also potentially on-site.

[0067] These components may then be integrated into the building unit 10 at the same off-site location. However, they could then be transported to another off-site location or transported on-site for final assembly. In this regard, the outer side walls 16, corner columns (not shown), corner castings (not shown), bottom rail 80 (see Stage 6 of Figure 1 ) and a top rail are all welded together.

[0068] The step of painting all (or substantially all) the steel is then undertaken with an approved coating system to achieve 50 year durability as typically required.

[0069] The floor 30 is also delivered to the living compartment 30 assembly site at this time.

[0070] All elements required for manufacturing the building unit 10 are then transported to the same location for final assembly.

STAGE 2 - LIVING COMPARTMENT (also known as an internal room POD)

[0071 ] This stage involves turning the floor structure over and screwing Magnesium Oxide Board (MgO) or equivalent to the underside thereof to provide the desired fire rating. [0072] The floor structure is then rotated back to its correct orientation, so that plumbing waste pipes can be fitted in the floor structure and run to the shared floor space 44 (or corridor area).

[0073] The floor structure is then sheeted, following which the internal side walls 34 (provided in the form of panels) and end walls 36 are stood up and screwed together. The ceiling 32 (provided in several panels) is then installed and screwed into place.

[0074] Where a bathroom is required in each of the compartments 28, a moulded one-piece bathroom floor is installed in the bathroom. Composite wall panels are also installed in the bathroom and then sealed. Any front glass required in the bathroom is installed.

[0075] Flat pack kitchens/robes/desks/shelves and pin boards, as required, can then be assembled and installed.

[0076] Electrical wires can be run around the outside of the walls 34, 36 and ceiling 32 in PVC conduits and through openings (not shown) in the walls, and then sealed with fire proof caulking.

[0077] Hot and cold pipes can be run externally around of the walls 34, 36 and ceiling 32, and through openings in the walls and then sealed in place.

[0078] Sprinkler pipes (not shown) can be run on the top of the ceiling 32 and a dropper can be installed and sealed.

[0079] Windows 40 can then be installed, and a door and door frame can be installed in each doorway 42.

[0080] The process of fitting off items internally, such as electrical fittings, taps, lights, WC, vanity, basin, etc can then be undertaken; and floor coverings can be installed. [0081 ] All electrical and plumbing can then be cleaned and tested, and the compartments 28 and their contents can be shrink wrapped in plastic and transported to a completion site or directly to on-site if desired to do so.

[0082] This stage is also where the living compartment 28 is specifically identified and given a "Birth Certificate" which determines its specific intended usage and location.

STAGE 3 - COMPLETION

[0083] In the completion stage, the compartments 28 are lifted into position into a jig at the completion site; following which the outer side walls 16 are lifted into the jig and plug welded to the steel floor structure of the compartment 30.

[0084] The end wall panels 22 are then installed and welded to corner columns 82 (see Figs 2 and 3).

[0085] Following this, the roof tie beams 20 are installed to the top of the outer side walls 16, and floor beams 84 are installed in the space between and welded to the compartments 28.

[0086] Top rail beams 86 are also installed between and welded to the compartments 28.

[0087] Roof channels (not shown) are installed to accommodate magnesium oxide board ceiling to provide a suitable fire rating.

[0088] Waste pipes are then extended from each compartment 28 to a suitable riser location and connected together.

[0089] During this stage, flooring 72 is also installed to the shared floor space 44 passage, while access panels remain loose for connection pins to be installed on site. [0090] Magnesium oxide board is also installed to ceiling channels (not shown), and seals are added around the junctions of walls.

[0091 ] Cable trays are installed and extend services from each compartment to a centre cable tray ready for site connections.

[0092] Seals are then added to around then window and the end wall 36.

[0093] Any further repainting of the steel components may be undertaken, as necessary, during this stage. The area between the compartments 28, which includes the shared flooring 72, may be cleaned and shrink wrapped to limit the ingress of dirt and moisture.

[0094] The completed building units can then be collected and directly transported to on-site for incorporation into the overall building structure 12. Alternatively, completed units 10 may be temporarily stored in a storage facility, and obtained from the storage facility as and when required.

STAGE 4 - BUILDING STRUCTURE ASSEMBLY

[0095] By the end of Stage 3, Stage 4 can be undertaken. This involves the on- site process of stacking the building units 10 to create the desired building structure 12, and then connecting the units 10 together to substantially prevent relative movement between adjacent units.

[0096] The present invention provides numerous potential advantages when compared to conventional building structures, particularly when compared to conventional multi-story building structures.

[0097] It provides a way of reducing set up costs and overheads. It also potentially limits the size of the factory required to produce the building units.

[0098] It provides a mechanism for greater production cost certainty, as much of the associated work is undertaken off-site using domestic conditions and paying domestic wages; whereas in conventional construction techniques the workforce is predominantly on-site.

[0099] The present invention potentially greatly enhances the speed of construction of a structure/building, especially if multiple building units 10 can be produced at the same time, either within one factory or within more than one factory, if it is desired to do so.

[0100] The present invention potentially enhances quality assurance and quality control, because the factory-based production techniques associated in producing the compartments 28 and building units 10 lends itself to enhanced inspection processes.

[0101 ] A better quality product is also potentially achievable with the present invention, given that manufacture of the compartments 28 and units 10 can be undertaken by trusted tradesmen that are familiar with the product and the expected level of finish.

[0102] The compartments 28 and unit 10 production facilities can be located as desired, and need not be proximate to the building site, since it is possible to easily transport the completed compartments 28 and units on the back of a truck or semi- truck trailer.

[0103] Since a majority of the production process for both the compartments 28 and units 10 is undertaken within a factory, it is possible to maintain a measure of confidentiality of many of the associated production processes. Maintaining confidentiality is difficult or impossible to achieve with conventional building techniques associated with multi-storey construction techniques, given that construction happens on-site in the presence of a large number of tradesmen and other individuals.

[0104] The present invention also potentially removes the need to employ a large and unfamiliar workforce if constructing a (multi-storey) building overseas. This is because much of the production can be undertaken in local specialist factories. Then the completed or substantially completed building units 10 can then be shipped overseas and quickly assembled on-site to construct the desired (multi-story) building.

[0105] The present invention is potentially more attractive to financers, who may be more attracted to the involvement of a local manufacturing facility and work force.

[0106] The present invention is also advantageous from the point of view that it provides a mechanism to relatively easily replace a building unit 10 in the event that it is damaged or requires modification.

[0107] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.

Claims

CLAIMS:

1 . A building unit of a modular building structure, the building unit including:

an outer wall assembly having a pair of opposing outer side walls;

the outer side walls each including an upper edge,

a set of tie beams with each tie beam for connecting to and extending between the upper edge of each outer side wall;

a pair of opposing outer end walls, the outer end walls for connecting to and extending between the outer side walls;

a pre-assembled living compartment, the living compartment including a floor and a ceiling, and an internal wall assembly including a pair of opposing internal side walls and a pair of opposing internal ends walls connected to and extending between the floor and the ceiling, and the internal side walls and the internal end walls defining a floor space of the living compartment;

wherein the outer wall assembly is assembled about the pre-assembled living compartment when completing construction of the building unit.

2. A building unit of a modular building structure according to claim 1 , wherein the building unit includes a pair of pre-assembled living compartments, with the living compartments separated by a shared floor.

3. A building unit of a modular building structure according to claim 1 or 2, wherein the outer end walls and outer side walls are manufactured from profiled sheet steel.

4. A building unit of a modular building structure according to any one of the preceding claims, wherein the pre-assembled living compartment includes fixtures and fittings.

5. A modular building structure including a plurality of building units of the type defined in any one of the preceding claims, wherein at least two building units are provided in a stacked arrangement, and the stacked building units are connected together.

6. A method of manufacturing a building unit of a modular building structure, the method including the steps of:

assembling a living compartment of the building unit, the living compartment including a floor, a ceiling and an internal wall assembly;

the internal wall assembly including a pair of opposing internal side walls connected to and extending between the floor and the ceiling, and a pair of opposing internal end walls connected to and extending between the floor and the ceiling, the internal side walls and the internal end walls defining a floor space of the living compartment; lifting the living compartment and placing it into a jig;

lifting a pair of opposing outer side walls and placing them into the jig on opposing sides of the living compartment;

connecting the outer side walls to the floor

connecting each tie beam of a set of tie beams between an upper edge of each outer side wall; and

connecting a pair of opposing outer end walls to and extending between the outer side walls and to the floor.

7. A method of manufacturing a building unit according to claim 6, wherein connecting the outer side walls to the floor involves welding, connecting each tie beam between the upper edge of each outer side wall involves welding, and connecting the opposing end walls to and extending between the outer side walls and floor involves welding.

8. A method of manufacturing a building unit according to claim 6 or 7, wherein the method includes the step of assembling a second living compartment of the building unit; and lifting the second living compartment and placing it into the jig prior to lifting the pair of opposing outer side walls into the jig.

9. A method of manufacturing a building unit according to claim 8, including fitting a shared floor between the living compartment and the second living compartment.

10. A method of manufacturing a building unit according to any one of claims 6 to 9, wherein connecting the opposing outer end walls to and extending between the outer side walls includes welding a corner connector between each respective pair of outer end walls and outer side walls.

1 1 . A method of manufacturing a modular building structure, wherein the method includes manufacturing a plurality of building units according to any one of claims 6 to 10, and including stacking and then connecting together two or more of the building units to create the modular building structure.